In the manufacture of cartons during a blanking operation, small sheets of paper material having specific profiles are cut out of larger sheets of paper material. These smaller sheets are known as carton blanks which are later formed into cartons and/or boxes.
As shown in FIGS. 1 and 2, in a die cutting machine 10, the blanks are cut, but not removed from a large sheet 12 of paper material. After the blanks have been cut at a cutting station 14, the large sheet layout 12 is pulled into a stripping station 15, where small pieces of waste in between the blanks are removed, and then to the blanking station 16 where the sheet is positioned over a frame which includes openings which correspond in size, shape and position to the profile of the carton blank layout.
At the blanking station 16, an upper tool is used in combination with the lower frame to knock the carton blanks from the sheet of paper material while holding the scrap material that surrounds the blanks. In particular, as shown in FIG. 3, a male blanker 20 includes a plurality of presser members 22A, 22B, 22C, 22D, 22E secured to a support plate/board 24, and the presser members 22A-22E are dimensioned to be the same shape and slightly smaller than the blanks 26A, 26B, 26C, 26D, 26E of a large sheet 12 supported upon a female blanker 28. Next to and between the presser members 22A-22E are a plurality of prior art standard pressers having presser rails 30. (Only one of the identical six illustrated presser rails in FIG. 3 is identified by the reference number 30 to avoid confusion.) Each prior art flat presser includes two mount housings 32, 34 that secure the presser rail 30 to the support plate 24. Each mount housing 32, 34 includes a guide strut 36, 38 that is secured within the mount housing by a spring biasing mechanism such as a captured coil spring (not shown), and the guide struts 36, 38 are secured to the presser rail 30. The spring biasing mechanism forces the presser rail 30 in a direction away from the support plate 24 and mount housings 32, 34.
As is well known, in operation the support plate 24 is moved against the sheet 12 as shown in FIG. 4 so that the presser rail 30 secures and stabilizes the carton blank scrap surrounding the blanks as the presser members 22A-22E impact the blanks 26A-26E to force them to break apart from the large sheet 12 and move with gravity assistance and guided by stationary joggers (not shown) to blank stacking piles 40A, 40B, 40C, 40D, 40E. After the blanks 26A-26E are removed from the large sheet 12, the sheet is referred to as blanking scrap. As is apparent, the faster the large sheet 12 can be processed by the male and female blankers 20, 28, the more cost efficient the blanking operation becomes.
As discussed above, in order to securely hold the carton blank scrap, known presser rails are interconnected to the support plate 24 by mount housings 32, 34 and guide struts 36, 38. As shown in FIGS. 3 and 4, each guide cylinder 32, 34 biases the presser rail 30 downwardly away from the support plate 24, and are mounted to the support plate 24 such that the mount housings 32, 34 project upwardly from the support plate. 24. However, it is desirable to eliminate any components projecting above the support plate 24 and instead provide interior mounted flat pressers/presser assemblies for a number of reasons. First, for tool storage purposes, an upper tool having interior mounted pressers takes up less space. This is particularly advantageous in locations where storage space is limited. Secondly, many existing die cutting machines are built in such a manner that the upper tool slides into the blanking station of the machine. Any component projecting upwardly from the support plate would interfere with such sliding action. Therefore, only interior mounted flat pressers can be used with such systems.
In addition, during the cutting operation, perimeters of the blanks are cut out using a continuous steel knife configuration of the blank profile. The blanks are usually held in the sheet 12 with nicks. Nicks are small areas around the perimeter where the knife is removed, usually with a small grinding wheel or chisel. Multiple nicks are usually placed around the blanks to carry the sheet into the blanking station 16 where the nicks are pulled apart during the blanking cycle. As the machine speed increases, more nicks may have to be added to the existing cutting tool to help hold the blanks in place. More nicks may hold the sheet together but they can also cause problems when the sheet is transferred to the blanking station 16. Therefore, it is desirable for a machine operator to have the ability to easily add a flat presser to the support plate 24 while the board is still on press. Prior art pressers, however, make it difficult to add pressers onto a support board without cutting a custom profile into the support plate 24 for mounting. In addition, prior art pressers are usually large, not customizable, and there is often insufficient space on the support plate for mounting any additional pressers to increase support and stabilization of the carton blank scrap during the blanking operation. In particular, known presser assemblies are often arranged in static rows, which allow for limited, if any, customization of presser geometry, i.e., the arrangement of pressers on the support plate.